An inductor is a representative passive element configuring an electronic circuit together with a resistor and a capacitor to remove noise. The inductor is combined with a capacitor that uses electromagnetic characteristics to configure a resonance circuit amplifying a signal in a specific frequency band, a filter circuit, or the like.
Recently, as miniaturization and thinness of information technology (IT) devices such as various communications devices, display devices, or the like, has been accelerated, research into technology for miniaturizing and thinning various elements such as an inductor, a capacitor, a transistor, and the like, used in these IT devices has been continuously conducted. Therefore, earlier inductors have been rapidly replaced by inductors having a small size, high density, and capable of being automatically surface-mounted, and a thin film type inductor, in which a mixture of magnetic powders and a resin is formed on coil patterns formed by plating, has been developed.
As a size of the thin film type inductor in which internal coil patterns are formed on upper and lower surfaces of a thin film type insulating substrate as described above is decreased, a volume of the inductor is decreased, a number of turns of the coil is decreased, and a space in which the coil may be formed is decreased. As an area in which the coil is formed is decreased, it is difficult to secure sufficient inductance, thereby decreasing inductance L and a quality factor Q.
A coil device in which a conductor pattern is embedded in a magnetic layer, in order to improve electrical properties while satisfying the requirement for miniaturization and thinness, is disclosed in the following Patent Document 1.